This application claims priority under 35 U.S.C. xc2xa7xc2xa7119 and/or 365 to 2000-258084 and 2000-274398 filed in Japan on Aug. 28, 2000 and Sep. 11, 2000; the entire content of which is hereby incorporated by reference.
The present invention relates to oil and fat compositions used as general-purpose cooking oils. In particular, the present invention relates to oil and fat compositions containing polyglycerol fatty acid esters, having a high suitability for cooking and exhibiting an excellent antifoaming effect while they are used for cooking.
As heat-cooking oils and fats for deep-frying and stir-frying, there have been used soybean oil, rapeseed oil, corn oil, cotton seed oil, rice bran oil, safflower oil, sunflower oil, sesame oil, olive oil, coconut oil, palm oil, lard and modified oils (transesterified oils and hydrogenated oils) prepared from them alone or in the form of a mixture of two or more of them.
In deep-frying in an oil or fat, a vapor is usually formed from a material being fried and, as a result, foams are formed. While the frying is repeated, the oil or fat is deteriorated and the foaming thereof is accelerated by an influence of ingredients eluted from the materials in the course of the deep-frying. When the foaming is serious, the materials are hidden by the foams and they cannot be seen, and the foams overflow from the pan to make the cooking operation dangerous. Accordingly, the amount of the material that can be deep-fried in the oil is limited. Particularly when the material to be deep-fried contains eggs or meats, the oil or fat is rapidly deteriorated. For controlling the foaming of the oil in the course of the deep-frying, a silicone oil has been added to the oil. However, the use of the silicone oil is recently avoided because the effect thereof is limited and the biodegradability thereof is only low.
A mixed oil of coconut oil and soybean oil and a transesterified oil prepared from medium length fatty acid triglycerides and rapeseed oil foam relatively easily to form a large quantity of the foams. The foaming of triglycerides comprising both fatty acids having 6 to 12 carbon atoms and fatty acids having 14 to 22 carbon atoms cannot be controlled even by the addition of the silicone.
The object of the present invention is to provide oil and fat compositions used as general-purpose cooking oils having a long deep-frying life, which compositions have a controlled foaming in the course of the frying and also good cooking properties.
After intensive investigations made for the purpose of attaining the above-described object, the inventors have found that when a specified polyglycerol fatty acid ester is incorporated in the oil and fat compositions, it becomes easy to remove the foam and the cooking properties of the compositions can be improved. The present invention has been completed on the basis of this finding.
Namely, the present invention relates to oil and fat compositions which comprises triglycerides as the main components and at least 0.01% by mass of one or more polyglycerol fatty acid esters having an average degree of polymerization of 6 to 30 and an average degree of substitution of 4 to 32. In the present invention, the higher the unsaturated fatty acid content of the fatty acids constituting the polyglycerol fatty acid esters, the better. The oil and fat compositions wherein fatty acids constituting the triglycerides are both those having 6 to 12 carbon atoms and those having 14 to 22 carbon atoms are preferred because the effects thereof are remarkable.